diff -r 000000000000 -r 6474c204b198 js/src/yarr/PageBlock.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/yarr/PageBlock.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,90 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ *
+ * ***** BEGIN LICENSE BLOCK *****
+ * Copyright (C) 2010 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#ifndef yarr_PageBlock_h
+#define yarr_PageBlock_h
+
+#include <stddef.h>
+#include <stdint.h>
+
+namespace WTF {
+
+size_t pageSize();
+inline bool isPageAligned(void* address) { return !(reinterpret_cast<intptr_t>(address) & (pageSize() - 1)); }
+inline bool isPageAligned(size_t size) { return !(size & (pageSize() - 1)); }
+inline bool isPowerOfTwo(size_t size) { return !(size & (size - 1)); }
+
+class PageBlock {
+public:
+    PageBlock();
+    PageBlock(const PageBlock&);
+    PageBlock(void*, size_t);
+
+    void* base() const { return m_base; }
+    size_t size() const { return m_size; }
+
+    operator bool() const { return !!m_base; }
+
+    bool contains(void* containedBase, size_t containedSize)
+    {
+        return containedBase >= m_base
+            && (static_cast<char*>(containedBase) + containedSize) <= (static_cast<char*>(m_base) + m_size);
+    }
+
+private:
+    void* m_base;
+    size_t m_size;
+};
+
+inline PageBlock::PageBlock()
+    : m_base(0)
+    , m_size(0)
+{
+}
+
+inline PageBlock::PageBlock(const PageBlock& other)
+    : m_base(other.m_base)
+    , m_size(other.m_size)
+{
+}
+
+inline PageBlock::PageBlock(void* base, size_t size)
+    : m_base(base)
+    , m_size(size)
+{
+}
+
+} // namespace WTF
+
+using WTF::pageSize;
+using WTF::isPageAligned;
+using WTF::isPageAligned;
+using WTF::isPowerOfTwo;
+
+#endif /* yarr_PageBlock_h */